The invention relates generally to gaskets and more particularly to a method to seal the ends of the fabric in a radio frequency interference (RFI) gasket and the gasket made by such method.
Conventional RFI shielding gaskets are formed with an electrically conductive fabric outer covering over a foam interior. Conventional die-cut fabric over foam gaskets typically have an open end in the fabric which can permit RF leakage. One way to reduce leakage is by sealing the ends of all six sides. This can be done by creating complex fabric shapes and folding and sealing the complex shape over the foam. This results in high labor costs and reduces output over time. It also results in the waste of the electrically conductive fabric.
Accordingly, it is desirable to provide an improved shielding gaskets with sealed ends which overcomes drawbacks of the prior art.
Generally speaking, in accordance with the invention, a fabric over foam gasket and method of construction are provided. The fabric can be disposed around a foam body and the ends can be heat sealed or sealed with an adhesive to provide high shielding properties. To form gaskets in accordance with the invention, a length of electrically conductive fabric is extended, a foam body is disposed on the fabric with edge portions of the fabric extending sideways beyond the edge of the foam body. The edge portions are then folded over the foam body and joined, such as by heat sealing. The fabric is then cross-cut and the cross-cut ends are sealed, such as by adhesive or heat sealing to provide a foam gasket completely covered with conductive fabric. The cutting and sealing can be accomplished in a single step with a hot knife. The fabric covered foam can then be die cut to the shape of the foam gasket and the outer edges will remain completely covered with the fabric.
A gasket in accordance with preferred embodiments of the invention preferably comprises an inner supporting structure having a top, a bottom, a pair of sidewalls in the length direction extending from the top to the bottom and a pair of sidewalls in the width direction extending from the top to the bottom and fabric, preferably having conductive properties, covering the top, the bottom, the pair of sides in the width direction and the pair of sides in the length direction. The fabric preferably extends continuously from the top, to the sides in the length direction to the bottom and is sealed at the sides in the width direction and the gasket preferably has electric wave shielding properties.
A preferred method of forming a gasket in accordance with preferred embodiments of the invention preferably comprises providing a length of fabric preferably having electrically conductive properties having a top surface and a bottom surface and first and second edge regions extending in the length direction and adhesive on a portion of the top surface along at least a first edge region and repeated adhesive stripes extending at least partially from edge to edge on the top surface, perpendicular to the length direction, disposing gasket bodies between the repeated adhesive stripes extending in the edge to edge direction between the first and second edge regions; folding the second edge region of the fabric over the top of the gasket body and folding the first edge, which has adhesive on the top surface thereof over the gasket body, such that the adhesive on the top surface of said other side is in contact with what had been the bottom surface of the second edge region, cutting the fabric cross-wise at the adhesive stripes, the cut location intermediate the adhesive stripe; and sealing the adhesive in the cross-wise direction, to provide a fabric covered gasket in which the fabric covers the top, bottom sides in the width direction and sides in the length direction of the gasket body. The fabric covered body can then be die cut and the edges will have fabric covering to provide effective shielding capabilities.
Accordingly, it is an object of the invention to provide an improved RF shielding gasket.
Another object of the invention is to provide electrically shielding gaskets in a more convenient and simple manner.
The invention accordingly comprises the several steps and the relation of one or more of such steps with respect to each of the others, and in the article possessing the features, properties and the relation of elements, which are exemplified in the following detailed disclosure, and the scope of the invention will be indicated in the claims.